I. Field of the Invention
The present invention relates to a polyamide rheological additive and a solution containing the additive. The present invention also relates to a thickened composition containing the additive.
II. Description of the Prior Art
The art has constantly sought materials which may be used to control the rheological properties of various compositions. One type of material which has been shown to be useful to thicken various organic compositions is organomodified clay. Exemplary U.S. patents which describe different kinds of organomodified (otherwise known as organophilic) clays are U.S. Pat. Nos. 4,081,496, 4,105,578, 4,116,866, 4,193,806, 4,208,218, 4,216,135, 4,287,086, 4,391,637, 4,410,364, 4,412,018, 4,434,075, 4,434,076, 4,450,095 and 4,517,112.
Other types of rheological additives have been designed to thicken aqueous based compositions. Such additives can be based on polyurethanes such as disclosed in U.S. Pat. Nos. 4,079,028, 4,155,892, 4,436,862 and 4,499,233.
Certain types of polyamides have also been employed as rheological additives. Thus, for example, U.S. Pat. No. 4,462,926 discloses a thixotropising agent for unsaturated polyester resins consisting of at least one cyclohexylamide of a saturated fatty acid which contains at least 10 carbon atoms and one or more oligomeric ester amides which have an average molecular weight of from 600 to 3,000, a content of carboxylic acid amide groups of from 1.5 to 15% by weight and a content of carboxylate groups of from 2 to 13% by weight.
A different type of polyamide thixotropic agent is set forth in U.S. Pat. No. 3,131,201 which describes a resinous composition which is the reaction product of an alkyl diamine having from 2 to 6 carbon atoms and two terminal primary amines with a copolymer formed by the reaction of a glyceride of a polyunsaturated fatty acid having an iodine value above 130 and a conjugated alicyclic diene hydrocarbon monomer.
While urelated to a rheological additive, U.S. Pat. No. 2,410,788 describes fatty amide polymers which are suitable for modifying the properties of textile fibers. The polymers are resinous or semi-resinous materials in which dialcohol substituted carboamido compounds carrying side chains containing polyamino acid amide radicals are linked together by reaction with polybasic acids.
In U.S. Pat. No. 3,037,871, a polyamide resin binder for printing inks is obtained from a combination of dimerized fatty acids and dimerized rosin acids with an alkylene diamine having from 2 to 6 carbon atoms, preferably ethylene diamine.
U.S. Pat. No. 3,957,733 sets forth an engineering plastic which is a polyamide of a 19 carbon diacid and trimethylhexamethylene diamine.
Finally, U.S. Pat. No. 4,062,819 describes polyamide blends having improved flow characteristics and rheological properties which are formed from a nylon-type polyamide and a minor amount of a polyamide derived from a high molecular weight dibasic acid. The second polyamide is more specifically obtained by the reaction of a long-chain dibasic acid containing 18 or more carbon atoms and a diamine or mixture of diamines.
Despite the numerous types of rheological additives known in the art, an ongoing search has been made for new rheological additives which are highly efficient and are readily dispersible in the composition to be thickened. The present invention is a result of such investigation.